Two studies are being conducted which will investigate attentional factors in auditory signal detection. The studies are being run simultaneously and are based upon preliminary experiments conducted in our laboratory. One study investigates the significance of stimulus change on the processing of auditory signals embedded in a masking noise, and investigates the nature of the temporal, frequency, and channel aspects of stimulus change effects. The other study investigates the ability of observers to process simultaneously or sequentially independent stimulus information to two or more conceptually different input channels. The nature and significance of any limits on the ability of the observers to time-share will be determined. Since the various frequency detection and discrimination tasks employed differ in the required use of short-term memory, the importance of this factor will be examined. These studies should delineate and significantly clarify the role of attention in the processing of auditory stimulus information. BIBLIOGRAPHIC REFERENCES: Ahroon, W.A., & Pastore, R.E. Failure of selective attention in simple recognition tasks: Critical band effects. Journal of the Acoustical Society of America, 1975, 58, S84 (A). Puleo, J.S., & Pastore, R.E. Attentional factors in simultaneous two-channel auditory signal detection. Journal of the Acoustical Society of America, 1976, 59, in press (A).